Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$65.56	9.371%	$71.7036	$71.70	$71.70	$71.70
Purchase #2	$241.73	5.304%	$254.5514	$254.55	$254.55	$254.60
Purchase #3	$57.44	12.632%	$64.6958	$64.70	$64.70	$64.70
Purchase #4	$157.33	9.357%	$172.0514	$172.05	$172.05	$172.10
Purchase #5	$56.97	3.859%	$59.1685	$59.17	$59.15	$59.20
Purchase #6	$18.93	10.398%	$20.8983	$20.90	$20.90	$20.90
Purchase #7	$77.86	6.497%	$82.9186	$82.92	$82.90	$82.90
7 purchase totals =	$675.82		$725.9876	$725.99	$725.95	$726.10